This procurement will produce a study to assess the feasibility of using biologic markers of semen to detect condom malfunction in human studies. The ultimate goal of this effort is to develop a testing procedure that can be undertaken by an unsupervised study subject and which has high sensitivity and specificity for detecting semen that has breached the condom barrier through condom slippage, leakage, or breakage during intercourse. Such a test could be utilized as an endpoint in a study of condom efficacy and would provide information that both complements and supersedes that found from studies using pregnancy or diseases as outcomes. The objectives of this study are to measure the least detectable amount of two markers for semen (prostatic acid phosphatase antigen and prostate specific antigen), determine that this amount can be differentiated from any background level, to standardize a post-coital self-sampling protocol, and to assess the usefulness of one or both of these tests as evidence of condom slippage, leakage, or breakage.